1. Field of the Invention
This invention relates in general to pumps and more particularly to a sonic pressure wave pump having a heat generating mechanism for use in heating underground formations and elevating the heated liquids to the ground surface.
2. Description of the Prior Art
Oil wells which are capable of producing only heavy crude oils having a tar-like viscosity, such as those rated at about eleven or so gravity, or higher, have remained caped due to the inability of existing equipment and methods for extracting such oils from the ground in acceptable quantities and at reasonable costs. Even when petroleum is bringing high prices and is in relatively short supply, treating such wells and pumping the oil therefrom remains unprofitable.
Part of the problem associated with extracting the heavy tar-like oils from the ground is the type of pumps which have traditionally been used for oil pumping tasks. The traditional pumps, sometimes referred to as "walking beam pumps" are very expensive to install, operate and maintain. In addition to this, the walking beam pumps simply won't pump the heavy oil without the well being treated in some manner to reduce the viscosity of the heavy oil.
Among the methods that have been used to treat a well so that the heavy oils can be pumped, are injecting solvents or other chemical fluids into the wells, injecting live steam, and the like. Such well treatments have successfully enabled the heavy oils to be pumped, but the extra costs involved and the minimum quantities of oil that can be pumped using such methods has, to the best of my knowledge, caused such well treating to be abandoned. This, of course, resulted in the extensive caping of oil wells of this type.
In addition to the walking beam pumps, another basic approach in pumps has been proposed with a very limited amount of success. Such pumps, which may be classified as "hydraulic pumps", operate by imparting intermittent hydraulic pressure waves on a column of liquid contained in pump tubing which extends from an above ground location to a subterranean source of the liquid to be pumped. The hydraulic pressure waves are generated by an above ground mechanism which reciprocally impacts the column of liquid and, in addition, cyclically opens and closes a liquid delvery port at the above ground location. The hydraulic pressure waves which are generated in this manner, are transmitted by the column of liquid to a downhole pumping device for operation thereof. The downhole pumping device usually includes a plunger or similar mechanism which is biased upwardly by suitable springs and has a central passage formed axially therethrough with a one-way check valve located in the axial passage. When the hydrualic pressure waves impinge on the plunger, it will move down through the liquid to be pumped against the bias of the springs. Such downward movement of the plunger will open the check valve and allow the liquid being pumped to move into the axial passage. The subsequent up strokes of the plunger which occur, under the influence of the biasing springs, between the intermittent hydraulic pressure waves, closes the check valve and causes a general upward movement of the liquid column with the upper end of the column discharging some of the liquid through the cyclically opened delivery port.
Examples of pumping mechanisms which operate generally in the above described maner are disclosed fully in U.S. Pat. Nos. 2,379,539; 2,355,618; 2,428,460; 2,572,977; 2,751,848 and 3,277,381. These pumps critically depend on ideal adjustments of input frequency relative to the length of the pump tubing in which the liquid column is contained. That is, resonant timing. Further, these prior art pumps are seriously limited as to their pumping capacity due to fluid friction, inertia of the liquid, and the like. These shortcomings have kept these types of prior art pumps from achieving any appreciable amount of commercial success and are inoperative in pumping oil of the above mentioned tar-like viscosity.
More recently, another type of pump has been developed which is commonly referred to as a "sonic pump". These pumps employ a special type of above ground generator which cyclically impacts a standing column of liquid contained in the pump tubing to provide a sonic pressure wave as opposed to the above described hydraulic pressure wave. Exactly how these types of pumps work is unknown. It is believed that the sonic pressure waves move downwardly in a spiral-like path about the periphery of the liquid column and impinge on the plunger device of the down-hole pumping mechanism causing it to operate much in the same manner as the plunger used in the above described hydraulic pump. However, instead of the plunger of the sonic pump lifting the column of liquid, it is believed that the liquid is carried to the surface by the sonic pressure waves which are reflected off of the plunger device and move upwardly in a spiral-like path centrally through the column of liquid.
These sonic pumps are fully disclosed in U.S. Pat. Nos. 4,295,799; 4,341,505; 4,381,177; 4,398,870; 4,449,892; 4,460,320; and 4,492,528. Although these pumps have proven to be successful in pumping both oil and water at relatively low installation, operating and maintenance costs, they, like the other pumps discussed briefly above, cannot pump the heavy tar-like oils in the absence of some sort of well treatment.
Therefore, a new and improved pumping device with downhole heating capabilities is needed to overcome some of the problems and shortcomings associated with prior art attempts at pumping heavy oils having tar-like viscosities.